Add note about default Android version for testbed.

Author: freakboy3742

docs/platforms.md

@@ -233,7 +233,7 @@ machine – for example, if you're building on an ARM64 machine, then you can te
 ARM64 wheel. Wheels of other architectures can still be built, but testing will
 automatically be skipped.
 
-Any arguments specified using [`test-execution`](options.md#test-execution) will be passed as arguments to the Python script that starts the [testbed project](https://github.com/python/cpython/blob/main/Android/README.md#testing). cibuildwheel will automatically start the testbed project with `--site-packages` and `--cwd` arguments matching your test environment, as well as enabling verbose output with `-v` if [`build_verbosity`](options.md#build_verbosity) is enabled. The most common additional arguments to use will be `--managed minVersion` or `--managed maxVersion`, specifying the use of a managed Android emulator with the minimum or maximum supported Android version; or `--connected <serial>`, specifying the use of an existing booted Android emulator or device.
+Any arguments specified using [`test-execution`](options.md#test-execution) will be passed as arguments to the Python script that starts the [testbed project](https://github.com/python/cpython/blob/main/Android/README.md#testing). cibuildwheel will automatically start the testbed project with `--site-packages` and `--cwd` arguments matching your test environment, as well as enabling verbose output with `-v` if [`build_verbosity`](options.md#build_verbosity) is enabled. The most common additional arguments to use will be `--managed minVersion` or `--managed maxVersion`, specifying the use of a managed Android emulator with the minimum or maximum supported Android version; or `--connected <serial>`, specifying the use of an existing booted Android emulator or device. By default, the testbed project will run with `--managed maxVersion`.
 
 Running an emulator requires the build machine to either be bare-metal or support
 nested virtualization. CI platforms known to meet this requirement are: